Correctly guard against the gcc version in these two memory unit tests.
Correctly guard against the gcc version in these two memory unit tests.

jaredhoberock/thrust,jaredhoberock/thrust,andrewcorrigan/thrust-multi-permutation-iterator,egaburov/thrust,sdalton1/thrust,sarvex/thrust,jaredhoberock/thrust,thrust/thrust,thrust/thrust,andrewcorrigan/thrust-multi-permutation-iterator,thrust/thrust,egaburov/thrust,jaredhoberock/thrust,sdalton1/thrust,sarvex/thrust,andrewcorrigan/thrust-multi-permutation-iterator,thrust/thrust,jaredhoberock/thrust,sarvex/thrust,sdalton1/thrust,egaburov/thrust,thrust/thrust